import java.util.HashSet;
import java.util.Locale;
import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 25228
 * Date: 2024-10-10
 * Time: 8:21
 */
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        QuadraticSolver quadraticSolver = new QuadraticSolver();
        CostEstimator costEstimator = new CostEstimator();
        Pentagon pentagon=new Pentagon();
        Robot robot=new Robot();
        String s;
        s=scanner.nextLine();
    }
}

        class QuadraticSolver {
            public void solve(double a, double b, double c) {
                if (a == 0) {
                    if (b == 0) {
                        System.out.println("invalid");
                    } else {
                        double x = -c / b;
                        System.out.println(1); // 一个解
                        String s = String.format("%6f", x);
                        System.out.println(s);
                    }
                } else {
                    double discriminant = b * b - 4 * a * c;

                    if (discriminant < 0) {
                        System.out.println("invalid");
                    } else if (discriminant == 0) {
                        System.out.println(1);
                        double x1 = -b / (2 * a);
                        String s = String.format("%6f", x1);
                        System.out.println(s);
                    } else {
                        System.out.println(2);
                        double x1 = (-b + Math.sqrt(discriminant)) / (2 * a);
                        double x2 = (-b - Math.sqrt(discriminant)) / (2 * a);
                        if (x1 > x2) {
                            double temp = x1;
                            x1 = x2;
                            x2 = temp;
                        }
                        String s = String.format("%6f %6f", x1, x2);
                        System.out.println(s);
                    }
                }
            }
        }

        class CostEstimator {
            public double estimate(double weight) {
                if (weight > 20 || weight < 0) {
                    return -1;
                }
                if (weight <= 1) {
                    return 3.5;
                } else if (weight <= 3) {
                    return 5.5;
                } else if (weight <= 10) {
                    return 8.5;
                } else {
                    return 10.5;
                }
            }
        }

        class Pentagon {
            double getArea(double r) {
                return (5 * Math.pow(2 * r * Math.sin(Math.PI / 5), 2)) / (4 * Math.tan(Math.PI / 5));
            }
        }

        class Robot {
            public void sayHello(String name) {
                System.out.println("Hello! My name is " + name + "!");
            }

            public void dance() {
                System.out.println("I will start dancing now!");
            }

            public void sayGoodbye() {
                System.out.println("Bye!");
            }
        }

        class Palindrome {
            public static boolean check(String s) {
                String s2 = s.toLowerCase();
                StringBuilder s3 = new StringBuilder();
                for (int i = 0; i < s2.length(); i++) {
                    if (Character.isLetterOrDigit(s2.charAt(i))) {
                    s3.append(s2.charAt(i));
                    }
                }
                int i = 0;
                int j = s3.length() - 1;
                while (i < j) {
                    if (s3.charAt(i) != s3.charAt(j)) {
                        return false;
                    } else {
                        i++;
                        j--;
                    }
                }
                return true;
            }
        }

        class MorseCode {
            public static int translate(String words) {
                HashSet<String> set = new HashSet<>();
                StringBuilder stringBuilder = new StringBuilder();
                for (char c : words.toCharArray()) {
                    if (c != ' ') {
                        stringBuilder.append(c);
                    } else {
                        // 当遇到空格时，将当前单词转换为摩尔斯电码并添加到set中
                        String morseCode = convertToMorse(stringBuilder.toString());
                        set.add(morseCode);
                        stringBuilder.setLength(0);
                    }
                }
                //添加最后一个单词
                String morseCode = convertToMorse(stringBuilder.toString());
                set.add(morseCode);
                return set.size();
            }

            public static String convertToMorse(String words) {
                String[] strings = new String[]{".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".---", "-.-", ".-..", "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--", "-..-", "-.--", "--.."};
                StringBuilder stringBuilder = new StringBuilder();
                for (int i = 0; i < words.length(); i++) {
                    stringBuilder.append(strings[words.charAt(i) - 'a']);
                }
                return stringBuilder.toString();
            }
        }


